1
FN6305.6
ISL6545, ISL6545A
5V or 12V Single Synchronous Buck
Pulse-Width Modulation (PWM) Controller
The ISL6545, ISL6545A makes simple work out of
implementing a complete control and protection scheme for a
DC/DC stepdown converter driving N-Channel MOSFETs in a
synchronous buck topology. Since it can work with either 5V or
12V supplies, this one IC can be used in a wide variety of
applications within a system. The ISL6545, ISL6545A
(hereafter referred to as “ISL6545x”, except as needed)
integrates the control, gate drivers, output adjustment,
monitoring and protection functions into a single 8 Ld SOIC or
10 Ld DFN package.
The ISL6545x provides single feedback loop, voltage-mode
control with fast transient response. The output voltage can be
precisely regulated to as low as 0.6V, with a maximum
tolerance of ±1.0% over-temperature and line voltage
variations. A selectable fixed frequency oscillator (ISL6545 for
300kHz; ISL6545A for 600kHz) reduces design complexity,
while balancing typical application cost and efficiency.
The error amplifier features a 20MHz gain-bandwidth
product and 9V/µs slew rate which enables high converter
bandwidth for fast transient performance. The resulting
PWM duty cycles range from 0% to 100%.
Protection from overcurrent conditions is provided by
monitoring the r
DS(ON)
of the lower MOSFET to inhibit PWM
operation appropriately. This approach simplifies the
implementation and improves efficiency by eliminating the
need for a current sense resistor.
Pinout
ISL6545, ISL6545A
(8 LD SOIC)
TOP VIEW
ISL6545, ISL6545A
(10 LD 3x3 DFN)
TOP VIEW
Features
• Operates from +5V or +12V Supply Voltage (for bias)
- 1.0V to 12V V
IN
Input Range (up to 20V possible with
restrictions; see Input Voltage Considerations)
- 0.6V to V
IN
Output Range
- Integrated Gate Drivers use V
CC
(5V to 12V)
- 0.6V Internal Reference; ±1.0% tolerance
• Simple Single-Loop Control Design
- Voltage-Mode PWM Control
- Drives N-Channel MOSFETs
- Traditional Dual Edge Modulator
• Fast Transient Response
- High-Bandwidth Error Amplifier
- Full 0% to 100% Duty Cycle
• Lossless, Programmable Overcurrent Protection
- Uses Lower MOSFET’s r
DS(ON)
• Small Converter Size in 8 Ld SOIC or 10 Ld DFN
- 300kHz or 600kHz Fixed Frequency Oscillator
- Fixed Internal Soft-Start, Capable into a Pre-biased
Load
- Integrated Boot Diode
- Enable/Shutdown Function on COMP/SD Pin
- Output Current Sourcing and Sinking
• Pb-Free (RoHS Compliant)
Applications
• Power Supplies for Microprocessors or Peripherals
- PCs, Embedded Controllers, Memory Supplies
- DSP and Core Communications Processor Supplies
• Subsystem Power Supplies
- PCI, AGP; Graphics Cards; Digital TV
- SSTL-2 and DDR/DDR2/DDR3 SDRAM Bus
Termination Supply
• Cable Modems, Set Top Boxes, and DSL Modems
• Industrial Power Supplies; General Purpose Supplies
• 5V or 12V-Input DC/DC Regulators
• Low-Voltage Distributed Power Supplies
5
6
8
7
4
3
2
1
UGATE
GND
PHASE
FB
VCC
COMP/SD
BOOT
LGATE/OCSET
1
BOOT
UGATE
N/C
GND
PHASE
COMP/SD
FB
N/C
2
3
4
5
LGATE/OCSET
10
9
8
7
6
VCC
GND
Data Sheet
March 3, 2011
CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.
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